Solubilization of Itraconazole by Surfactants and Phospholipid-Surfactant Mixtures: Interplay of Amphiphile Structure, pH and Electrostatic Interactions

Author(s):  
Zahari Vinarov ◽  
Gabriela Gancheva ◽  
Nikola Burdzhiev ◽  
Slavka S. Tcholakova

Although surfactants are frequently used in enabling formulations of poorly water-soluble drugs, the link between their structure and drug solubilization capacity is still unclear. We studied the solubilization of the “brick-dust” molecule itraconazole by 16 surfactants and 3 phospholipid:surfactant mixtures. NMR spectroscopy was used to study in more details the drug-surfactant interactions. Very high solubility of itraconazole (up to 3.6 g/L) was measured in anionic surfactant micelles at pH = 3, due to electrostatic attraction between the oppositely charged (at this pH) drug and surfactant molecules. <sup>1</sup>H NMR spectroscopy showed that itraconazole is ionized at two sites (2+ charge) at these conditions: in the phenoxy-linked piperazine nitrogen and in the dioxolane-linked triazole ring. The increase of amphiphile hydrophobic chain length had a markedly different effect, depending on the amphiphile type: the solubilization capacity of single-chain surfactants increased, whereas a decrease was observed for double-chained surfactants (phosphatidylglycerols). The excellent correlation between the chain melting temperatures of phosphatidylglycerols and itraconazole solubilization illustrated the importance of hydrophobic chain mobility. This study provides rules for selection of itraconazole solubilizers among classical single-chain surfactants and phospholipids. The basic physics underpinning the described effects suggests that these rules should be transferrable to other “brick-dust” molecules.

2020 ◽  
Author(s):  
Zahari Vinarov ◽  
Gabriela Gancheva ◽  
Nikola Burdzhiev ◽  
Slavka S. Tcholakova

Although surfactants are frequently used in enabling formulations of poorly water-soluble drugs, the link between their structure and drug solubilization capacity is still unclear. We studied the solubilization of the “brick-dust” molecule itraconazole by 16 surfactants and 3 phospholipid:surfactant mixtures. NMR spectroscopy was used to study in more details the drug-surfactant interactions. Very high solubility of itraconazole (up to 3.6 g/L) was measured in anionic surfactant micelles at pH = 3, due to electrostatic attraction between the oppositely charged (at this pH) drug and surfactant molecules. <sup>1</sup>H NMR spectroscopy showed that itraconazole is ionized at two sites (2+ charge) at these conditions: in the phenoxy-linked piperazine nitrogen and in the dioxolane-linked triazole ring. The increase of amphiphile hydrophobic chain length had a markedly different effect, depending on the amphiphile type: the solubilization capacity of single-chain surfactants increased, whereas a decrease was observed for double-chained surfactants (phosphatidylglycerols). The excellent correlation between the chain melting temperatures of phosphatidylglycerols and itraconazole solubilization illustrated the importance of hydrophobic chain mobility. This study provides rules for selection of itraconazole solubilizers among classical single-chain surfactants and phospholipids. The basic physics underpinning the described effects suggests that these rules should be transferrable to other “brick-dust” molecules.


Author(s):  
V. Prasad Shastri ◽  
Christopher Pino ◽  
Michael A. Scherer ◽  
Chenxia Monica. Guan

Author(s):  
Sumant Saini ◽  
Yashwant .

Solid dispersions are one of the most promising strategies to improve the oral bioavailability of poorly water soluble drugs. By reducing drug particle size to the absolute minimum, and hence improving drug wettability, bioavailability may be significantly improved. This article reviews the various preparation techniques for solid dispersion and compiles some of the recent technology transfers. The different types of solid dispersions based on the molecular arrangement have been highlighted. Some of the practical aspects to be considered for the preparation of solid dispersions, such as selection of carrier, solvent and methods of physicochemical characterization, along with an insight into the molecular arrangement of drugs in solid dispersions are also discussed. In this review, it is intended to discuss the recent advances related on the area of solid dispersions.


Author(s):  
Sudarshan Singh ◽  
S S Shyale ◽  
H G Sandip

In present investigation liquisolid compact technique is investigated as a tool for enhanced dissolution of poorly water-soluble drug Ketoconazole. The liquisolid tablets were formulated with liquid medications, namely Propylene Glycol (PG) drug concentrations, 60% w/w, 70% w/w and 80% w/w. Avicel pH102 was used as a carrier material, Aerosil 200 as a coating material and Sodium starch glycollate as a super-disintegrant. Quality control tests, such as uniformity of tablet weight, uniformity of drug content, tablet hardness, friability test, disintegration and dissolution tests were performed to evaluate prepared tablets. For further confirmation of results the liquisolid compacts were evaluated by XRD and FTIR studies to prove that, solubility of Ketoconazole has been increased by liquisolid compact technique. From the results obtained, it was be speculated that such systems exhibit enhanced drug release profiles due to increased wetting properties and surface of drug available for dissolution. As liquisolid compacts demonstrated significantly higher drug release rates, in PG as compared to directly compressible tablets and conventional wet granulation, we lead to conclusion that it could be a promising strategy in improving the dissolution of poor water soluble drugs and formulating immediate release solid dosage forms.  


2017 ◽  
Vol 23 (3) ◽  
pp. 467-480 ◽  
Author(s):  
Satyanarayan Pattnaik ◽  
Kamla Pathak

Background: Improvement of oral bioavailability through enhancement of dissolution for poorly soluble drugs has been a very promising approach. Recently, mesoporous silica based molecular sieves have demonstrated excellent properties to enhance the dissolution velocity of poorly water-soluble drugs. Description: Current research in this area is focused on investigating the factors influencing the drug release from these carriers, the kinetics of drug release and manufacturing approaches to scale-up production for commercial manufacture. Conclusion: This comprehensive review provides an overview of different methods adopted for synthesis of mesoporous materials, influence of processing factors on properties of these materials and drug loading methods. The drug release kinetics from mesoporous silica systems, the manufacturability and stability of these formulations are reviewed. Finally, the safety and biocompatibility issues related to these silica based materials are discussed.


2017 ◽  
Vol 23 (3) ◽  
pp. 350-361 ◽  
Author(s):  
Hisham Al-Obaidi ◽  
Mridul Majumder ◽  
Fiza Bari

Crystalline and amorphous dispersions have been the focus of academic and industrial research due to their potential role in formulating poorly water-soluble drugs. This review looks at the progress made starting with crystalline carriers in the form of eutectics moving towards more complex crystalline mixtures. It also covers using glassy polymers to maintain the drug as amorphous exhibiting higher energy and entropy. However, the amorphous form tends to recrystallize on storage, which limits the benefits of this approach. Specific interactions between the drug and the polymer may retard this spontaneous conversion of the amorphous drug. Some studies have shown that it is possible to maintain the drug in the amorphous form for extended periods of time. For the drug and the polymer to form a stable mixture they have to be miscible on a molecular basis. Another form of solid dispersions is pharmaceutical co-crystals, for which research has focused on understanding the chemistry, crystal engineering and physico-chemical properties. USFDA has issued a guidance in April 2013 suggesting that the co-crystals as a pharmaceutical product may be a reality; but just not yet! While some of the research is still oriented towards application of these carriers, understanding the mechanism by which drug-carrier miscibility occurs is also covered. Within this context is the use of thermodynamic models such as Flory-Huggins model with some examples of studies used to predict miscibility.


2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Shivarani Eesam ◽  
Jaswanth S. Bhandaru ◽  
Chandana Naliganti ◽  
Ravi Kumar Bobbala ◽  
Raghuram Rao Akkinepally

Abstract Background Increasing hydrophilicity of poorly water-soluble drugs is a major challenge in drug discovery and development. Cocrystallization is one of the techniques to enhance the hydrophilicity of such drugs. Carvedilol (CAR), a nonselective beta/alpha1 blocker, used in the treatment of mild to moderate congestive heart failure and hypertension, is classified under BCS class II with poor aqueous solubility and high permeability. Present work is an attempt to improve the solubility of CAR by preparing cocrystals using hydrochlorothiazide (HCT), a diuretic drug, as coformer. CAR-HCT (2:0.5) cocrystals were prepared by slurry conversion method and were characterized by DSC, PXRD, FTIR, Raman, and SEM analysis. The solubility, stability, and dissolution (in vitro) studies were conducted for the cocrystals. Results The formation of CAR-HCT cocrystals was confirmed based on melting point, DSC thermograms, PXRD data, FTIR and Raman spectra, and finally by SEM micrographs. The solubility of the prepared cocrystals was significantly enhanced (7.3 times), and the dissolution (in vitro) was improved by 2.7 times as compared to pure drug CAR. Further, these cocrystals were also found to be stable for 3 months (90 days). Conclusion It may be inferred that the drug–drug (CAR-HCT) cocrystallization enhances the solubility and dissolution rate of carvedilol significantly. Further, by combining HCT as coformer could well be beneficial pharmacologically too.


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